System and method for reducing drop placement errors at perimeter features on an object in a three-dimensional (3d) object printer

ABSTRACT

A slicer in a material drop ejecting three-dimensional (3D) object printer generates machine ready instructions that operate components of a printer, such as actuators and an ejector having at least one nozzle, to form features of an object more precisely than previously known. The instructions generated by the slicer control the actuators to move the ejector and a platform on which the object is formed relative to one another at a constant velocity to form edges of the feature.

CROSS-REFERENCED APPLICATION

This application cross-references U.S. patent application Ser. No.__/______, which is entitled “System And Method For Reducing DropPlacement Errors At Perimeter Features On An Object In AThree-Dimensional (3D) Object Printer, which was filed on mm/dd/yyyy,the entirety of which is hereby expressly incorporated by reference.

TECHNICAL FIELD

This disclosure is directed to three-dimensional (3D) object printersthat eject drops of material to form three-dimensional (3D) objects and,more particularly, to the formation of object features that requirevelocity changes in the relative motion of the components of the objectprinter.

BACKGROUND

Three-dimensional printing, also known as additive manufacturing, is aprocess of making a three-dimensional solid object from a digital modelof virtually any shape. Many three-dimensional printing technologies usean additive process in which an additive manufacturing device formssuccessive layers of the part on top of previously deposited layers.Some of these technologies use ejectors that eject drops of meltedmaterials, such as photopolymers or elastomers. The printer typicallyoperates one or more ejectors to form successive layers of thethermoplastic material that form a three-dimensional printed object witha variety of shapes and structures. After each layer of thethree-dimensional printed object is formed, the plastic material iscured so it hardens to bond the layer to an underlying layer of thethree-dimensional printed object. This additive manufacturing method isdistinguishable from traditional object-forming techniques, which mostlyrely on the removal of material from a work piece by a subtractiveprocess, such as cutting or drilling.

Recently, some 3D object printers have been developed that eject dropsof melted metal from one or more ejectors to form 3D objects. Theseprinters have a source of solid metal, such as a roll of wire orpellets, that is fed into a heating chamber where the solid metal ismelted and the melted metal flows into a chamber of the ejector. Anuninsulated electrically conducting wire is wrapped around the chamber.An electrical current is passed through the conductor to produce anelectromagnetic field that causes the meniscus of the melted metal at anozzle of the chamber to separate from the melted metal within thechamber and be propelled from the nozzle. A platform opposite the nozzleof the ejector is moved in a X-Y plane parallel to the plane of theplatform by a controller operating actuators so the ejected metal dropsform metal layers of an object on the platform and another actuator isoperated by the controller to alter the position of the ejector orplatform in the vertical or Z direction to maintain a constant distancebetween the ejector and an uppermost layer of the metal object beingformed. This type of metal drop ejecting printer is also known as amagnetohydrodynamic printer.

In these known 3D object printers that eject material drops to formobjects, the printhead and the platform on which the object is formedmove relative to one another in an X-Y plane and in a Z plane that isperpendicular to the X-Y plane. A program typically called a slicerprocesses a three-dimensional model or other digital data model of theobject to be produced to generate data identifying each layer of theobject and then generate machine-ready instructions for execution by theprinter controller in a known manner. Execution of these instructionscauses the controller to operate the components of the printer to movethe platform and the printhead relative to one another while operatingthe printhead to eject drops of material that form the objectcorresponding to the digital data model. The generation of themachine-ready instructions can include the production of intermediatemodels, such as when a CAD digital data model for an object is convertedinto a STL object layer data model, or other polygonal mesh or otherintermediate representation, which can in turn be processed to generatemachine instructions, such as g-code, for fabrication of the device bythe printer.

The machine instructions, when executed by the printer controller,generate signals for the actuators that move the printhead and theplatform supporting the object relative to one another and the signalsthat operate the one or more ejectors in the printhead. Some featureswithin a layer or on the perimeter of a layer require the relativemovement between the ejector and the platform to decelerate as the endof the feature is approached and then that movement is accelerated forcompletion of the contour of the feature. The instructions, whenexecuted by the controller for the printer, stop or almost stop therelative movement of the ejector and platform at one edge of the featureand then the instructions, when executed, cause the relative movement tobe along a path that is coincident with the other edge of the feature.This acceleration and deceleration in the relative movement of theejector and platform can produce errors in the placement of the dropsforming the feature. These errors can cause irregularities in thefeature, especially when the change in relative motion velocity occursat an edge of the feature. To attenuate the production of theseirregularities, the relative movement occurs along a path that joins thefirst edge of the feature to the second edge of the feature. Thus, thefeature is slightly rounded. Not only is the feature rounded rather thanprecise but the time required for forming the corner is increased by thedeceleration and acceleration of the ejector. Being able to placematerial drops more precisely for the formation of object features inadditive manufacturing machines would be beneficial.

SUMMARY

A new method of operating a material drop ejecting 3D object printer canplace material drops more precisely for the formation of object featuresthan known 3D object printers. The method includes identifying a featureto be formed in an object layer of an object to be formed on a platformusing an object data model of the object to be formed, and moving anejector and the platform relative to one another at a constant velocityto form the identified feature in the object layer of the object beingformed on the platform.

A new material drop ejecting 3D object printer more precisely placesmaterial drops to form features that require ejector directional changesthan previously known 3D object printers. The material drop ejecting 3Dobject printer includes an ejector having at least one nozzle that isconfigured to eject drops of a material, a platform positioned oppositethe ejector head, at least one actuator operatively connected to atleast one of the platform and the at least one ejector, the at least oneactuator being configured to move the at least one of the platform andthe at least one ejector relative to one another, and a controlleroperatively connected to the ejector head and the at least one actuator.The controller is configured to identify a feature to be formed in anobject layer of an object to be formed on the platform using an objectdata model of the object to be formed, and move the ejector and theplatform relative to one another at a constant velocity to form theidentified feature in the object layer of the object being formed on theplatform.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of a method of operating amaterial drop ejecting 3D object printer and a new material dropejecting 3D object printer that more precisely places material drops forforming features requiring velocity changes in the relative motion ofthe ejector and the platform on which an object is formed thanpreviously known 3D object printers are explained in the followingdescription, taken in connection with the accompanying drawings. Themethod and printer described below use a slicer that generatesinstructions for relatively moving the ejector and the platform at aconstant velocity during formation of a feature or by ejecting a lastdrop of a first edge of the feature at a predetermined location and thenmoving the ejector outside of the feature before the relative movementof the ejector and the platform returns the ejector to the predeterminedposition for ejecting the first drop of a second edge of the feature.The intersection of the first and second edges forms a perimeter of thefeature more precisely. Additionally, the time to form the sharp corneris decreased over previously known printers since the constant velocityof the relative movement between the ejector and the platform does notchange during feature formation.

FIG. 1 depicts a metal drop ejecting 3D metal object printer that moreprecisely places material drops to form features than previously known3D object printers that required velocity changes in the relativemovement of an ejector and a platform to form the features.

FIG. 2 is an illustration of a tool path for relative movement of theejector and the platform to form a feature with the printer of FIG. 1.

FIG. 3 is a flow diagram of a process implemented by a slicer program inthe printer of FIG. 1 that forms features more precisely than previouslyknown 3D object printers by moving the ejector and the platform relativeto one another at a constant velocity during feature formation.

FIG. 4 is a flow diagram of a process implemented by a slicer program inthe printer of FIG. 1 that forms features more precisely than previouslyknown 3D object printers by moving the ejector and the platform relativeto one another to predetermined locations identified by encoder valuesto form the edges of the feature.

DETAILED DESCRIPTION

For a general understanding of a 3D object printer and its operationthat form features more precisely than previously known 3D objectprinters that require velocity changes to form the features, referenceis made to the drawings. In the drawings, like reference numeralsdesignate like elements.

FIG. 1 illustrates an embodiment of a melted metal 3D object printer 100that is configured with a slicer that generates machine readyinstructions for moving the platform and ejector relative to one anotherto form features more precisely than previously known 3D objectprinters. As used in this document, the term “feature” means a structurewithin an object layer that required previously known 3D object printersto change the velocity of the relative movement between the ejector andthe platform to form the structure. Although the printer 100 is depictedwith a single nozzle, it could be configured with multiple nozzles ormultiple ejector heads. Also, while the description below is made withreference to the metal drop ejecting 3D object printer 100 of FIG. 1,the controller 136 configured with the slicer program can be used with asingle nozzle or multi-nozzle 3D object printer that ejects drops ofother materials, such as thermoplastic material.

In the printer of FIG. 1, drops of melted bulk metal are ejected from anejector having a single nozzle in an ejector head 104 and drops from thenozzle form lines for layers of an object 108 on a platform 112. As usedin this document, the term “bulk metal” means conductive metal availablein aggregate form, such as wire of a commonly available gauge or pelletsof macro-sized proportions. A source of bulk metal 160, such as metalwire 130, is fed into the ejector head and melted to provide meltedmetal for a chamber within the ejector head. An inert gas supply 164provides a pressure regulated source of an inert gas 168, such as argon,to the chamber of melted metal in the ejector head 104 through a gassupply tube 144 to prevent the formation of metal oxide within theejector head or along the flight of the melted metal drops toward theobject being formed.

The ejector head 104 is movably mounted within Z-axis tracks 116A and116B in a pair of vertically oriented members 120A and 120B,respectively. Members 120A and 120B are connected at one end to one sideof a frame 124 and at another end to one another by a horizontal member128. An actuator 132 is mounted to the horizontal member 128 andoperatively connected to the ejector head 104 to move the ejector headalong the Z-axis tracks 116A and 166B. The actuator 132 is operated by acontroller 136 to maintain a distance between the single nozzle of theejector in the ejector head 104 and an uppermost surface of the object108 on the platform 112.

Mounted to the frame 124 is a planar member 140, which can be formed ofgranite or other sturdy material to provide reliably solid support formovement of the platform 112. Platform 112 is affixed to X-axis tracks144A and 144B so the platform 112 can move bidirectionally along anX-axis as shown in the figure. The X-axis tracks 144A and 144B areaffixed to a stage 148 and stage 148 is affixed to Y-axis tracks 152Aand 152B so the stage 148 can move bidirectionally along a Y-axis asshown in the figure. Actuator 122A is operatively connected to theplatform 112 and actuator 122B is operatively connected to the stage148. Controller 136 operates the actuators 122A and 122B to move theplatform along the X-axis and to move the stage 148 along the Y-axis tomove the platform in an X-Y plane that is opposite the ejector head 104.Performing this X-Y planar movement of platform 112 as drops of moltenmetal 156 are ejected toward the platform 112 forms a line of meltedmetal drops on the object 108. Controller 136 also operates actuator 132to adjust the vertical distance between the ejector head 104 and themost recently formed layer on the substrate to facilitate formation ofother structures on the object. While the molten metal 3D object printer100 is depicted in FIG. 1 as being operated in a vertical orientation,other alternative orientations can be employed. Also, while theembodiment shown in FIG. 1 has a platform that moves in an X-Y plane andthe ejector head moves along the Z axis, other arrangements are possibleto achieve relative movement between the ejector in the ejector head andthe platform on which an object is formed. For example, either theejector head 104, the platform 112, or both can be configured to achieverelative movement between the ejector head 104 and the platform 112 inthe X-Y plane and along the Z axis. An encoder 114 is operativelyconnected to the controller 136. The encoder 114 is configured togenerate positional data indicative of the position of the ejector inthe ejector head in relation to the platform as a result of the relativemovement between the ejector head and the platform. This positional datais used by the controller to control the relative movement of theejector head and the platform and to control the ejections of theejector as described more fully below.

The controller 136 can be implemented with one or more general orspecialized programmable processors that execute programmedinstructions. The instructions and data required to perform theprogrammed functions can be stored in memory associated with theprocessors or controllers. The processors, their memories, and interfacecircuitry configure the controllers to perform the operations previouslydescribed as well as those described below. These components can beprovided on a printed circuit card or provided as a circuit in anapplication specific integrated circuit (ASIC). Each of the circuits canbe implemented with a separate processor or multiple circuits can beimplemented on the same processor. Alternatively, the circuits can beimplemented with discrete components or circuits provided in very largescale integrated (VLSI) circuits. Also, the circuits described hereincan be implemented with a combination of processors, ASICs, discretecomponents, or VLSI circuits. During metal object formation, image datafor a structure to be produced are sent to the processor or processorsfor controller 136 from either a scanning system or an online or workstation connection for processing and generation of the ejector headcontrol signals output to the ejector head 104.

The controller 136 of the melted metal 3D object printer 100 requiresdata from external sources to control the printer for metal objectmanufacture. In general, a three-dimensional model or other digital datamodel of the object to be formed is stored in a memory operativelyconnected to the controller 136, or the controller can access through aserver or the like a remote database in which the digital data model isstored, or a computer-readable medium in which the digital data model isstored can be selectively coupled to the controller 136 for access. Thisthree-dimensional model or other digital data model is processed by aslicer program implemented with the controller to produce dataidentifying each layer of an object and then generate machine-readyinstructions for execution by the controller 136 in a known manner tooperate the components of the printer 100 and form the metal objectcorresponding to the model. The generation of the machine-readyinstructions can include the production of intermediate models, such aswhen a CAD digital data model for an object is converted into a STLobject layer data model, or other polygonal mesh or other intermediaterepresentation, which can in turn be processed to generate machineinstructions, such as g-code, for fabrication of the device by theprinter. As used in this document, the term “machine-ready instructions”means computer language commands that are executed by a computer,microprocessor, or controller to operate components of a 3D metal objectadditive manufacturing system to move the ejector head and the platformrelative to one another and to operate the ejector in the ejector headto form objects on the platform 112 with the material drops ejected bythe printer. The controller 136 executes the machine-ready instructionsto control the ejection of the material drops from the ejector head 104,the positioning of stage 148 and the platform 112, as well as thedistance between the ejector head 102 and the uppermost layer of theobject 108 on the platform 112.

In the printer of FIG. 1, the controller 136 is configured with a slicerprogram that generates machine ready instructions for forming featuresmore precisely than previously known. As used in this document, the term“edge of a feature” means a segment forming a portion of a perimeter ofa feature. As shown in FIG. 2, these generated instructions cause thecontroller 136 to move the ejector and the platform relative to oneanother at a constant velocity along a path that forms a first edge 204of a feature and along a return path 208 to the end of the first edge toform a second edge 216 of the feature in a layer of the object. Byprecisely placing the last drop of edge 204 at a predetermined locationof the feature and then precisely placing the first drop of the edge 216closely to the last drop of the edge 204 at the predetermined locationthe feature is formed more precisely. In one embodiment, the first dropof the second edge is positioned at about one-half of a diameter of anejected drop from the last drop of the first edge so the perimeter ofthe feature is continuously formed. To perform this placement, theadditionally generated machine ready instructions maintain the relativemovement of the ejector and the platform at a constant velocity alongthe entire path defined by first edge 204, the return path 208, 212, andthe second edge 216. Alternatively, the generated machine readyinstructions identify a first encoder value that identifies the positionof the last drop of the first edge and a second encoder value thatidentifies the position of the first drop of the second edge. While thereturn path is shown as being circular in FIG. 2, other path shapes,such as rectilinear, triangular, and polygonal can be used depending onthe topography in the vicinity of the edges of the feature. Otherinstructions cause the controller to regulate the ejection frequency ofthe ejector so the first and second edges are continuously formed. Thegeneration of these additional machine ready instructions that cause thecontroller to operate the components of the printer to performoperations other than those defined by the digital data model for theobject enable the printer to form features more precisely thanpreviously known machines. While the example shown in FIG. 2 depicts afeature in an external perimeter for a layer, the feature can be withinthe interior of a perimeter as well. Also, while the feature formed bylines 204 and 216 is a right angled feature, features can be formed withother angles, such as acute or obtuse angles.

A process for operating a material drop ejecting 3D object printer toform features more precisely than previously known printers is shown inFIG. 3. In the description of the process, statements that the processis performing some task or function refers to a controller or generalpurpose processor executing programmed instructions stored innon-transitory computer readable storage media operatively connected tothe controller or processor to manipulate data or to operate one or morecomponents in the printer to perform the task or function. Thecontroller 136 noted above can be such a controller or processor.Alternatively, the controller can be implemented with more than oneprocessor and associated circuitry and components, each of which isconfigured to form one or more tasks or functions described herein.Additionally, the steps of the method may be performed in any feasiblechronological order, regardless of the order shown in the figures or theorder in which the processing is described.

FIG. 3 is a flow diagram of a process 300 that operates a material dropejecting 3D object printer, such as printer 100, to form features moreprecisely than previously known printers. The process 300 begins withthe slicer receiving the digital data model for the object to beproduced (block 304). The slicer then generates object layer data forforming the layers of the object (block 308). The slicer then identifiesfeatures in object layer data for each layer of the object (block 312).Rather than generating machine ready instructions that decelerate therelative movement of the ejector head and the platform as the ejectorapproaches a turn in the perimeter of a feature as previously done, theslicer generates machine ready instructions that move the ejector headand the platform relative to one another at a constant velocity alongthe first edge of the feature, along a return path to the end of thefirst edge of the feature, and along a second edge of the feature (block316). Instructions are generated to move the ejector head to a positionopposite the end of the first edge of the feature (block 320) with otherinstructions that adjust the velocity of the ejector head and theplatform relative to one another along the second edge of the featureand the frequency of drop ejection to form the second edge at arelatively uniform density. When these instructions are executed,operation of the ejector in the ejector head commences at a positionabout one-half of a drop diameter past the end of the first edge of thefeature (block 324). Instructions for forming the remaining portion ofthe perimeter are generated in a known manner until another feature isidentified so the process can be repeated (block 328). This process isrepeated for each feature in a layer (block 332) and for each layer inthe object (block 336). When all of object layer data has beenprocessed, the machine ready instructions are executed by the controllerto operate the printer and form the object on the platform 112 (block340).

FIG. 4 is a flow diagram of a process that operates a material dropejecting 3D object printer, such as printer 100, to form features moreprecisely than previously known printers. The process 400 begins withthe slicer receiving the digital data model for the object to beproduced (block 404). The slicer then generates object layer data forforming the layers of the object (block 408). The slicer then identifiesfeatures in object layer data for each layer (block 412). Rather thangenerating machine ready instructions that decelerate the relativemovement of the ejector head and the platform as the ejector approachesa turn in the perimeter of a feature as previously done, the slicergenerates machine ready instructions that move the ejector head and theplatform relative to one another to form a first edge of the featurehaving its end identified by an encoder value for a position of the lastdrop ejected to form the first edge of the feature (block 416).Instructions are generated that move the ejector and the platformrelative to one another to return the ejector to the identified positionof the last drop in the first edge using encoder positional data (block420). Instructions are also generated for moving the ejector and theplatform relative to one another while operating the ejector to ejectdrops to form a second edge of the feature using encoder positional data(block 424). In one embodiment, the position of the first drop of thesecond edge is ejected within a merge distance of the last drop in thefirst edge. As used in this document, the term “merge distance” means adistance between the centers of adjacent drops on a surface that enablethe drops to form a continuous line. In one embodiment, the mergedistance is one-half of the diameter of the last drop ejected in thefirst edge of the feature. Instructions for forming the remainingportion of the perimeter are generated in a known manner until anotherfeature is identified so the process can be repeated (block 428). Thisprocess is repeated for each feature in a layer (block 432) and for eachlayer (block 436). When all of object layer data has been processed, themachine ready instructions are executed by the controller to operate theprinter and form the object on the platform 112 (block 440).

It will be appreciated that variants of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems, applications or methods.Various presently unforeseen or unanticipated alternatives,modifications, variations or improvements may be subsequently made bythose skilled in the art that are also intended to be encompassed by thefollowing claims.

What is claimed:
 1. A method of operating a material drop ejectingthree-dimensional (3D) object printer to form an object comprising:identifying a feature to be formed in an object layer of an object to beformed on a platform using an object data model of the object to beformed; and moving an ejector and the platform relative to one anotherat a constant velocity to form the identified feature in the objectlayer of the object being formed on the platform.
 2. The method of 1further comprising: moving the ejector and the platform relative to oneanother at the constant velocity to form a first edge of the feature. 3.The method of claim 2 further comprising: moving the ejector andplatform relative to one another at the constant velocity to positionthe ejector opposite an end of the first edge of the feature; and movingthe ejector and the platform relative to one another at the constantvelocity to form a second edge of the feature.
 4. The method of claim 3,the formation of the second edge further comprising: operating theejector to eject a first drop of the second edge of the feature within amerge distance of a last drop in the first edge of the feature.
 5. Themethod of claim 4, the positioning of the ejector opposite the end ofthe first edge of the feature further comprising: moving the ejector andthe platform relative to one another so the ejector moves away from theend of the first edge of the feature before the ejector is positionedopposite the end of the first edge of the feature.
 6. The method ofclaim 5, the positioning of the ejector opposite the end of the firstedge of the feature further comprising: moving the ejector and theplatform relative to one another along a circular path to the positionopposite the end of the first edge of the feature.
 7. The method ofclaim 5, the positioning of the ejector opposite the end of the firstedge of the feature further comprising: moving the ejector and theplatform relative to one another along a non-circular path to theposition opposite the end of the first edge of the feature.
 8. Themethod of claim 4 wherein the merge distance is approximately one-halfof a diameter of the last drop ejected at the end of the first edge ofthe feature.
 9. The method of claim 4 further comprising: moving theejector and the platform relative to one another to form the first edgeof the feature and the second edge of the feature at right angles to oneanother.
 10. The method of claim 4 further comprising: moving theejector and the platform relative to one another to form the first edgeof the feature and the second edge of the feature at acute angles to oneanother.
 11. The method of claim 4 further comprising: moving theejector and the platform relative to one another to form the first edgeof the feature and the second edge of the feature at obtuse angles toone another.
 12. The method of claim 1 wherein the ejector and theplatform move relative to one another to a position of the last drop ofthe first edge and to a position of the first drop of the second edgeusing positional data generated by an encoder.
 13. The method of claim 1further comprising: generating machine ready instructions for operatingcomponents of the 3D object printer to move the ejector and the platformrelative to one another and to operate the ejector to form the firstedge and the second edge of the feature; and executing the generatedmachine ready instruction to operate the components of the 3D objectprinter to move the ejector and the platform relative to one another andto operate the ejector to form the first edge and the second edge of thefeature.
 14. A material drop ejecting three-dimensional (3D) objectprinter comprising: an ejector having at least one nozzle that isconfigured to eject drops of a material; a platform positioned oppositethe ejector head; at least one actuator operatively connected to atleast one of the platform and the at least one ejector, the at least oneactuator being configured to move the at least one of the platform andthe at least one ejector relative to one another; and a controlleroperatively connected to the ejector head and the at least one actuator,the controller being configured to: identify a feature to be formed inan object layer of an object to be formed on the platform using anobject data model of the object to be formed; and move the ejector andthe platform relative to one another at a constant velocity to form theidentified feature in the object layer of the object being formed on theplatform.
 15. The printer of claim 14, the controller being furtherconfigured to: move the ejector and the platform relative to one anotherat the constant velocity to form a first edge of the feature.
 16. Theprinter of claim 15, the controller being further configured to: movethe ejector and platform relative to one another at the constantvelocity to position the ejector opposite an end of the first edge ofthe feature; and move the ejector and the platform relative to oneanother at the constant velocity to form a second edge of the feature.17. The printer of claim 16, the controller being further configured toform the second edge by: operating the ejector to eject a first drop ofthe second edge of the feature within a merge distance of a last drop inthe first edge of the feature.
 18. The printer of claim 17, thecontroller being further configured to position the ejector opposite theend of the first edge of the feature by: moving the ejector and theplatform relative to one another so the ejector moves away from the endof the first edge of the feature before the ejector is positionedopposite the end of the first edge of the feature.
 19. The printer ofclaim 18, the controller being further configured to position theejector opposite the end of the first edge of the feature by: moving theejector and the platform relative to one another along a circular pathto the position opposite the end of the first edge of the feature. 20.The printer of claim 18, the controller being further configured toposition the ejector opposite the end of the first edge of the featureby: moving the ejector and the platform relative to one another along anon-circular path to the position opposite the end of the first edge ofthe feature.
 21. The printer of claim 17 wherein the merge distance isapproximately one-half of a diameter of the last drop ejected at the endof the first edge of the feature.
 22. The printer of claim 17, thecontroller being further configured to: move the ejector and theplatform relative to one another to form the first edge of the featureand the second edge of the feature at right angles to one another. 23.The printer of claim 17, the controller being further configured to:move the ejector and the platform relative to one another to form thefirst edge of the feature and the second edge of the feature at acuteangles to one another.
 24. The printer of claim 17, the controller beingfurther configured to: move the ejector and the platform relative to oneanother to form the first edge of the feature and the second edge of thefeature at obtuse angles to one another.
 25. The printer of claim 14,the controller being further configured to: move the ejector and theplatform move relative to one another to a position of the last drop ofthe first edge and to a position of the first drop of the second edgeusing positional data generated by an encoder.
 26. The printer of claim14, the controller being further configured to: generate machine readyinstructions for operating components of the 3D object printer to movethe ejector and the platform relative to one another and to operate theejector to form the first edge and the second edge of the feature; andexecute the generated machine ready instructions to operate thecomponents of the 3D object printer to move the ejector and the platformrelative to one another and to operate the ejector to form the firstedge and the second edge of the feature.